Cotton Report 1998
ABOUT THE COLLECTION
The Cotton Report is one of several commodity-based agricultural research reports published by the University of Arizona.
This report, along with the Forage and Grain Report, was established by Hank Brubaker, Extension Agronomist, after seeing a similar report published by Texas A&M University in the mid-1970’s.
The purpose of the report is to provide an annual research update to farmers, researchers, and those in the agricultural industry. The research is conducted by University of Arizona and USDA-ARS scientists.
Both historical and current Cotton Reports have been made available in the UA Campus Repository as part of a collaboration between the College of Agriculture and Life Sciences and the University Libraries.
Contents for Cotton Report 1998
- The 1998 Cotton Advisory Program
- Date of Planting by Long Staple and Short Staple Variety Trial, Safford Agricultural Center, 1997
- Evaluation of Planting Date Effects on Crop Growth and Yield for Upland and Pima Cotton, 1997
- Evaluation of Irrigation Termination Affects on Upland Cotton, 1997
- Evaluation of 1997 Late-Season Crop Conditions
- Cotton Defoliation Evaluations, 1997
- Defoliation Tests with Ginstar at the Maricopa Agricultural Center in 1997
- Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1997
- Fruiting Distribution Patterns among Three Cotton Varieties under Irrigated Conditions
- Do PIX® Application Guidelines Change for Bt Cotton?
- Development of a Yield Projection Technique for Arizona Cotton
- Arizona Upland Cotton Variety Testing Program, 1997
- Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1997
- Marana Upland Test
- Short Staple Regional Cotton Variety Trials, Graham County, 1997
- Short Staple Regional Cotton Variety Trial, Safford Agricultural Center, 1997
- Short Staple Variety Trial, Greenlee County, 1997
- Short Staple Variety Trials in Cochise County, 1997
- Short Staple Cotton Advanced Strains Trial, Safford Agricultural Center, 1997
- 1997 Low Desert Upland Cotton Advanced Strains Testing Program
- Agronomic Evaluations of Transgenic Cotton Varieties
- Agronomic Evaluations of New Transgenic and Non Transgenic Cotton Varieties in La Paz and Mohave Counties
- Pima Regional Variety Test at the Maricopa Agricultural Center, 1997
- Marana Pima Test, 1997
- Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1997
- Upland Cotton Lint Yield Response to Several Soil Moisture Depletion Levels
- Irrigation Efficiencies and Lint Yields of Upland Cotton Growth at the Maricopa Agricultural Center, 1997
- Using Drainage Lysimeters to Evaluate Irrigation and Nitrogen Interactions in Cotton Production
- Field Determination of Permanent Wilting Point
- Survey of Cotton Weeds and Weed Control Practice in Arizona Upland Cotton Fields
- Preliminary Study of Cotton Weed Control Strategies Using Over-The-Top Herbicides
- Layby Mexican Sprangletop Control with Select (Clethodim) and Antagonism Resulting from Staple (Pyrithiobac Sodium) and Select Tank Mixed
- IPM/BMP Practices in Arizona Cotton
- Evaluation of B. T. Cotton Deployment Strategies and Efficacy against Pink Bollworm in Arizona
- Efficacy of Insecticides for Pink Bollworm and Cotton Leaf Perforator Control in Cotton Grown in the Low Desert Region of Arizona, 1997
- Correlation between Early Season Insecticide Control of Pink Bollworm and Other Pests and Subsequent Whitefly Applications near Gila Bend, AZ, 1997
- Effects of Entomopathogentic Nematodes on Pink Bollworm Mortality
- Late Season Pink Bollworm Pressure in the Top Crop of Bt and Non-Bt Cotton
- Whitefly Management in Arizona: Looking at Whole Systems
- Whitefly Management in Arizona: Conservation of Natural Enemies Relative to Insecticide Regime
- Whitefly Management in Arizona: Contribution of Natural Enemies to Whitefly Mortality
- 1997 Season Update on Resistance of Arizona Whiteflies to Synergized Pyrethroid and Select Non-Pyrethroid Insecticides
- Can Resistance to Chloronicotynl Insecticides be Averted in Arizona Field Crops?
- Voluntary Area-Wide Whitefly Monitoring Project Implementation 1995-1997, Gila Bend, AZ
- Silverleaf Whitefly Cotton Cultivator Preference
- Efficacy of Experimental Insecticides for Whitefly Control in Cotton, 1996
- Efficacy of Experimental Insecticides for Whitefly Control in Cotton, 1997
- Seasonal Distribution of Bemesia Honeydew Sugars on Pima and Upland Cotton Lint
- Effects of Cotton Ginning and Lint Cleaning on Sticky Cotton
- Integrated Lygus Management in Arizona
- Lygus Chemical Control: Are Combinations Sprays Worth It?
- Efficacy of Experimental Insecticides for Insect Control in Cotton Grown in the Low Desert Region of Arizona, 1997
- New Insights Regarding Estimating Lygus Susceptibility to Insecticides
- Systemic Insecticide Applications at Planting and First Square in Bt Cotton for Early Season Insect Control - La Paz and Mohave Counties
- Side-dress Temik® Effects on Lint Yields
- Nitrogen Management Experiments for Upland and Pima Cotton, 1997
- Evaluation of a Feedback Approach to Nitrogen and Pix Applications, 1997
- Comparison of the Two Methods for the Analysis of Petiole Nitrate Nitrogen Concentration in Irrigated Cotton
- Evaluation of a Nitrogen-15 Microplot Design in a Furrow Irrigated Row Crop System
- Potassium Fertilization of Upland and Pima Cotton (1991-1995, a five year project review)
- Mathematical Models of Potassium Release Kinetics for Sonoran Desert Soils of Arizona
- Evaluation of Calcium Soil Conditioners in an Irrigated Cotton Production System, 1997
- Foliar Fertilizer Evaluation on Upland Cotton, 1997
- Fungicide Treatment and Varietal Effects on Alternaria Leaf Spot of Pima Cotton
- Interactions Between Herbicides and Cotton Seedling Damping-off in the field
- Non-chemical Control of Cotton Seedling Damping-off in the Field
- Spatial Analysis of Aspergillus flabus S and L Strains
- Aflatoxin Contamination of Bt and Non-Bt Cottonseed
- Cotton Virus Diseases
- Diversity and Global Distribution of Whitefly-Transmitted Geminiviruses of Cotton
- Telone II® Following Grain Rotation for Nematode Control?
- Infection of Sorghum Varieties by the Cotton Root-knot Nematode, Meloidogyne incognita
Copyright © Arizona Board of Regents. The University of Arizona.
Whitefly Management in Arizona: Contribution of Natural Enemies to Whitefly Mortality(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Direct-observation studies were conducted to identify causes and estimate rates of mortality of whiteflies over the course of four generations between late June to early September in replicated experimental plots. In plots receiving no whitefly insecticides. predation and dislodgment were major sources of egg and nymphal mortality and overall survival from egg to adult ranged from 1-8.5%. Similar patterns were observed in plots treated with insect growth regulators. except that Knack caused high levels of egg inviability and Applaud was a major source of mortality in small nymphs during the second generation immediately following single applications of these materials. Mortality due to predation was generally lowest for eggs and nymphs in plots treated with a rotation of conventional insecticides reflecting disruption of the predator fauna. Parasitism was a very minor source of mortality throughout. The selective action of the IGRs enhances the abundance and activity of natural enemies resulting in high levels of whitefly control with minimal use of disruptive insecticides. Natural enemies likely contribute to the "extended" residual effects of IGRs so commonly reported by growers.
Infection of Sorghum Varieties by the Cotton Root-knot Nematode, Meloidogyne incognita(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Twentythree varieties of sorghum, Sorghum bicolor, were evaluated for susceptibility to the cotton root -knot nematode, Meloidogyne incognita race 3. Eggs per gram of root were used as a measure of nematode reproduction and host susceptibility. The nematode reproduced on all varieties tested Mean egg counts were lowest on the varieties Northrup King (NK) KS-737, MF.; NK 1580,M; NK Ks-735 M.F.; NK 714Y MF.; NK Lt. Bronze X 609 M; Ciba-NK C-1506, M; and Pioneer 8877, but these varieties are still considered to be hosts capable of sustaining or increasing nematode populations in cotton fields. All varieties were better hosts than cotton.
Telone II® Following Grain Rotation for Nematode Control?(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Nine field trials were conducted between 1994 and 1997 in Buckeye and Gila Bend, Arizona to determine the effect of soil fumigation with Telone II on the yield of cotton following rotation with Durum wheat. Telone was shank injected at two or more rates (0, 3, or 5 gal/acre) in fields previously maintained with a cotton-wheat-summer/winter fallow rotation. Eight fields were planted to Upland and one field to Pima cotton. Eight of the nine studies resulted in a statistically significant lint yield increase with the 5 gallon rate compared to the untreated check. Seven of the nine studies resulted in a positive net economic return on investment ranging from $0.78/acre to $103.29/acre. In one trial where all three rates were compared, yield at the 5 gallon rate was increased 141 lint lbs/ac compared to the 3 gallon rate which did not differ from the control.
Diversity and Global Distribution of Whitefly-Transmitted Geminiviruses of Cotton(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Geminivirus diseases of cotton are on the rise, worldwide, yet few have been studied in adequate detail to permit the implementation of rational approaches to disease control. The rising costs of managing the whitefly vector, coupled with substantial losses caused by geminivirus-incited diseases now hinder cotton production by requiring inputs that are beyond economic feasibility. The need for geminivirus disease resistant cultivars in diverse cotton producting areas and against different viral genotypes presents a new challenge. To meet this need, information about the identity, distribution, and relevant biotic characteristics of cotton -infecting geminiviruses is needed This project addresses this problem through the molecular analysis of the genomes of cotton-infecting geminivirus from cotton throughout the world Here, sequence similarities of the coat protein gene and of the non-coding IR/CR involved in regulating virus replication and transcription were examined by comparative sequence analysis to achieve virus identification. This is the first effort to determine virus identity and to map the distribution of geminiviruses on a global basis. The outcome of this effort will be a data base containing biotic and molecular information that will permit rapid and accurate geminivirus identification, and the selection of relevant viral species for development of cotton cultivars with disease resistance to the geminiviruses specific to individual production areas.
Cotton Virus Diseases(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Virus diseases of cotton have historically been of only sporadic importance to global cotton production. Recent devastating epidemics in Pakistan and other areas have brought new awareness to the potential for disaster of a pathogen once considered to be of a minor importance. Under changing conditions this pathogen (cotton leaf curl virus) has emerged as a serious problem in Pakistan and India. Cotton leaf curl virus does not occur in the United States or the rest of the western hemisphere but recent experience worldwide is a reminder that pathogens, such as this geminivirus, can be moved easily from one part of the world to another and therefor we need to be aware of the potential impact of such pathogens on local crops.
Aflatoxin Contamination of Bt and Non-Bt Cottonseed(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Transgenic Bt cotton varieties that are resistant to pink bollworm should sustain less feeding damage to bolls and cottonseed, compared to non-Bt varieties that are more susceptible to feeding damage by pink bollworm larvae. Prior to boll opening, the aflatoxin producing fungus Aspergillus flavus cannot penetrate undamaged cotton bolls. Thus resistance to pink bollworm could result in reduced aflatoxin contamination under high pink bollworm pressure. Cottonseed aflatoxin levels of Bt and non-Bt varieties were compared at various planting and harvest dates. Bt and non-Bt cotton varieties had similar cottonseed aflatoxin levels. Long season production systems favored high cottonseed aflatoxin levels, compared to short season production systems, regardles of the cotton variety grown.
Spatial Analysis of Aspergillus flabus S and L Strains(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)The distribution of S and L strains of Aspergillus flavus is more stable than previously realized. Analysis with GIS/geostatistics shows that patches of similar S strain incidence persist over years. This information will be exceptionally useful to programs involved with or planning large-scale treatments to reduce aflatoxin contamination because it can be used to spatially focus treatments.
Non-chemical Control of Cotton Seedling Damping-off in the Field(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)We conducted four field trials in April 1995 and 1996 in Arizona to compare the effectiveness of the following treatments to reduce cotton seedling damping-off incidence: 1) a soil drench of an isolate of the bacterium, Burkholderia cepacia (DI), recovered by us from cotton plants; 2) isolate D1 barley meal formulation; 3) Deny® seed treatment (a peat moss -based formulation of another isolate of B. cepacia, CCT Corp. Carlsbad, California); 4) Deny® soil drench; 5) Kodiak® seed treatment (a formulation of the bacterium, Bacillus subtilis, Gustafson Inc., Dallas, Texas); 6) a mixture of three fungicides Metalaxyl, Triadimenol, and Thiram seed treatment; and 7) a mixture of Metalaxyl, Triadimenol, Thiram, and Kodiak® seed treatment. Except for DI, the other products are being marketed for the control of cotton seedling damping-off Only DI soil drench and a mixture of the three fungicides seed treatment increased cotton stand significantly (P ≤ 0.05) in three of four field trials.
Interactions Between Herbicides and Cotton Seedling Damping-off in the field(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)We studied the impact of three pre plant herbicides, trifluralin, pendimethalin and prometryn on the incidence and the development of Rhizoctonia solani- induced cotton seedling damping-off in the field. In a field experiment conducted in Safford, Arizona, pre plant application of pendimethalin or prometryn but not trifluralin caused significant (P < 0.05) increases in disease incidence. In another field experiment in Tucson, Arizona, significant (P < 0.05) increase in disease incidence was observed in plots treated with prometryn and not in those treated with pendimethalin and trijuralin. In Tucson field experiment, application of herbicides also affected disease development as judged by the slope of disease progress curves.
Fungicide Treatment and Varietal Effects on Alternaria Leaf Spot of Pima Cotton(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)The effect of foliar treatments for prevention of Alternaria leaf spot was evaluated in the field on six varieties of Pima cotton. Disease was significantly reduced by protective sprays of mancozeb and micronized sulfur but not by foliar applications of urea in trials at the University of Arizona Safford Agricultural Center in Safford, AZ. Treatments had no significant effects on yields. Significantly fewer lesions developed on Pima variety UA 4 than on the other varieties. Disease pressure was relatively light, and even though scheduled preventive sprays with mancozeb were effective, fungicide applications probably would not increase yields under the environmental conditions of this experiment.
1997 Cottonseed Variety and Treatment Evaluation(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Three upland cotton varieties (Deltapine 5415, Stoneville 474, and SureGrow 125) were subjected to three seed treatments (non or control, standard commercial triple treated, and standard commercial plus Prevail added to the hopper box at 1 lb product /100 lb cottonseed) to determine seed germination and vigor in a Mohave Valley field prone to Rhizoctonia infection of cotton seedlings.
1997 Seed Treatment Evaluations(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken on two separate dates after emergence at all three locations and percent emergence (PEM) was calculated. Significant differences in percent emergence due to treatment were observed in the both sample dates at Marana and Safford. Maricopa showed very little significant differences due treatment.
Foliar Fertilizer Evaluation on Upland Cotton, 1997(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)A single field experiment was conducted in 1997 at the University of Arizona Yuma Valley Agricultural Center. The purpose of the experiment was to evaluate foliar applications of Macro Sorb (L form amino acids) and KeyPlex (chelated micronutrients and alpha keto amino acids) foliar fertilization materials on Upland cotton. Treatments consisted of various rates and times of application of the foliar materials based upon manufacturer recommendations. Results from this single experiment revealed no differences among treatments with respect to in-season plant measurements, tissue N concentrations, or lint yield.
Evaluation of Calcium Soil Conditioners in an Irrigated Cotton Production System, 1997(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)A single field experiment was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona in 1996 and 1997. NuCotn™ 33B was dry planted and watered -up on 15 April and 1 April in 1996 and 1997. Various rates and times of application of nitrogen (N) and calcium (Ca) from two sources [N-Cal™ (CO(NH₂)₂•CaC1₂) and CAN-17 (CaNO₃)] as well as a standard N source, UAN-32 [NH₄NO₃•CO(NH₂)₂] were used to evaluate the check In 1996 treatments 1, 2,and 3 each received a total of 280 lbs. N/acre, treatment 4 received a total of 210 lbs. N/acre, while treatment 5 received a total of 301 lbs. N/acre. Treatment 1 received only farm standard applications of UAN-32. Treatments 2 and 4 each received a total of 72 lbs. of Ca/acre. Treatment 5 received a total of 79 lbs. Ca/acre from N-Cal™ while treatment 3 received a total of 301 lbs. Ca/acre from CAN -17. Treatment 4 used a conservative N approach (UA guidelines). 1997 was similar to 1996 in the general nature of the experimental design, but different in its actual treatments. Treatments 2, 3, 4, and 5 each used N-Cal™ for the first two irrigation applications then UAN -32 for continued crop N needs. Treatment 4 used a conservative N approach (U A guidelines). Treatments 3 and 5 each received two foliar applications of N-Cal™ Foliar applications consisted of N-Cal™ mixed with urea for a 15-0-0-8 formula and applied on 22 July and 29 July via a high cycle applicator at a 5 gal/acre rate of N-Cal™ (carrier rate = 40 gal /acre). No significant differences were found among the various treatments in terms of plant growth, soil water content, ECₑ values, and sodium absorption ratios in 1996 or 1997. Lint yields were not significantly different in 1996 (P < 0.05) or 1997 (P < 0.05).
Mathematical Models of Potassium Release Kinetics for Sonoran Desert Soils of Arizona(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)The objective of this study was to determine the potassium (K) release kinetics of clay samples from 10 agricultural representative soils of Arizona by successive extraction using Ca-saturated cation resin. A 1993 physical and chemical characterization of the soils revealed that all soils contain smectite-mica K bearing minerals. Four mathematical models (power function, Elovich, parabolic diffusion and first-order) were used to describe the nonexchangeable K release reaction involving 700-hr cumulative reaction time. Comparison of the models using the coefficient of determination (r²) and the standard error of the estimate (SE) indicated that the Elovich and the power function equations overall displayed the best fit. The first-order rate and for the most part, the parabolic diffusion equation did not describe the K release very well. The constants a and b for the Elovich and the power function equations, which represent the intercept and the release rate of the nonexchangeable K respectively, are at least in the order of magnitude as those found by others in several previous studies.
Potassium Fertilization of Upland and Pima Cotton (1991-1995, a five year project review)(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)In an effort to provide information on the agronomic necessity of potassium (K) fertilization in Arizona cotton (Gossypium spp.) production, a five-year study was initiated in 1991 with a single field study located near Gila Bend. Subsequent study sites selected ranged from western (Yuma) to eastern (Safford) Arizona, which totaled 11 site years. Both Upland (G. hirsutum L.) and American Pima (G. barbadense L.) cotton were cultivated, using soil and foliar applications of K. In 1992, study sites included the Safford Ag. Center (SAC), Maricopa Ag. Center (MAC), and a Cooperator site at Coolidge. In 1993, the experiment stations sites were maintained (SAC and MAC) and Yuma Valley was added. The 1994 study sites included only the two experiment stations (SAC and MAC). In 1995, SAC and MAC were maintained, and a third location was a farmer cooperator site at Buckeye. The results from all studies (12) indicated no lint yield increases due to K fertilization at any of the locations with either Upland or Pima cotton. However, in 1995, at the Buckeye location, the result revealed a significant yield reduction due to the K foliar treatments. There were, however, no significant differences among soil as well as the soil-plus-foliar treated plots in the 1995 study at Buckeye.
Evaluation of a Nitrogen-15 Microplot Design in a Furrow Irrigated Row Crop System(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Two field experiments were conducted in Arizona in at two locations, Maricopa in 1991 (Casa Grande sandy loam) and Marana (Pima clay loam) in 1995. The purposes of the experiments were to evaluate the dimensions of an ¹⁵N microplot design used in a furrow irrigated row crop system. The experiments each utilized ammonium sulfate fertilizer with 5 atom % ¹⁵N enrichment applied at a rate of 56 kg N/ha in simulated side-dress band application during the early bloom stage of development of Upland cotton (Gossvpium barbadense L). At each location, microplots were 4, 1.02 m rows wide and 1.00 m in length. Whole plant samples were collected at specific locations within and near the microplots. Uptake of ¹⁵N by plants was uniform within microplots but declined symmetrically in relation to microplot borders. Collection of plant materials within 25 cm of microplot borders provided uniform ¹⁵N enrichment levels for determining fertilizer N uptake and recovery. Use of microplots with the dimensions of those used in this study are sufficient for collecting plant materials from a 1 m² area; consisting of two, 50 cm segments from the interior two rows of the four row microplot. This also allows for sufficient distance from the perimeter of the microplot to account for border effects.
Comparison of the Two Methods for the Analysis of Petiole Nitrate Nitrogen Concentration in Irrigated Cotton(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)A study was conducted in Arizona in 1997 with the objective of analyzing the accuracy of a recently developed portable nitrate meter (Cardy meter) to effectively measure petiole nitrate - nitrogen (NO₃-N) in irrigated cotton (Gossvpium sue.). This task was accomplished by performing correlation and linear regression analyses on NO₃-N concentrations of cotton petiole sap, as measured by the Cardy meter, against the standard procedure NO₃-N analysis, as measured by an ion selective electrode (ISE). Results revealed that the NO₃-N concentrations of petiole sap were highly correlated with dried petiole NO₃-N (pearson correlation coefficient = 0.96, P < 0.0001). A regression equation with an r² = 0.92 was derived: Y = 9.96X - 1170.86, where X and Y are NO₃-N in petiole sap (ppm) and dried petioles (ppm), respectively. These results suggest that the sap analysis using the Cardy meter is a potentially valuable tool to monitor the in-season N status of irrigated cotton.
Evaluation of a Feedback Approach to Nitrogen and Pix Applications, 1997(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)A single field experiment was conducted in 1997 at Marana, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on growth parameters) to both nitrogen (N) and mepiquat chloride (P1X) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height to node ratios (HNRs) with respect to established baselines for Arizona growing conditions. Scheduled and feedback FIX applications were made for a total of 0.75 and 1.50 pt./acre, respectively, with the scheduled treatments being initiated earlier in the fruiting cycle (early and peak bloom). Feedback PIX treatments consisted of a single 0.75 pt./acre application near peak bloom (approx. 2000 heat units after planting, HUAP, 86/55 °F threshold). Scheduled applications of fertilizer N totaled 150 lbs. N/acre from two applications and feedback N treatments received a total of 100 lbs. N/acre from two applications. Treatments consisted of all combinations of scheduled or feedback applications of both N and PIX. The highest lint yields were from treatments receiving PIX applications, with significant differences (P ≥ 0.05) between a check treatment (with no FIX applications) and several other treatments that did receive PIX applications. If FIX was applied, there were no significant differences between the scheduled or feedback approach. Applications of PIX in relation to increasing HNRs (feedback approach) are demonstrated and reinforced in this study.
Nitrogen Management Experiments for Upland and Pima Cotton, 1997(College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)Two field experiments were conducted in Arizona in 1997 at two locations (Maricopa and Marana). The Maricopa experiment has been conducted for eight consecutive seasons, the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for both Upland and Pima cotton. The experiments each utilized N management tools such as pre- season soil tests for NO₃⁻-N in- season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location.